ent-Labdane Diterpenoids from Andrographis paniculata - Journal of

Andrographis paniculata Nees (Acanthaceae), a well-known herbal medicine, ... The 70% acetone−water extract of the aerial parts of A. paniculata was...
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J. Nat. Prod. 2006, 69, 319-322

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ent-Labdane Diterpenoids from Andrographis paniculata⊥ Yun-Heng Shen,†,‡ Rong-Tao Li,† Wei-Lie Xiao,† Gang-Xu,† Zhong-Wen Lin,† Qin-Shi Zhao,† and Han-Dong Sun*,† State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, People’s Republic of China, and Graduate School of the Chinese Academy of Sciences, Beijing 100039, People’s Republic of China ReceiVed May 10, 2005

Six new ent-labdane diterpenoids, 3-O-β-D-glucopyranosyl-14,19-dideoxyandrographolide (1), 14-deoxy-17-hydroxyandrographolide (2), 19-O-[β-D-apiofuranosyl(1f2)-β-D-glucopyranoyl]-3,14-dideoxyandrographolide (3), 3-O-β-Dglucopyranosylandrographolide (4), 12S-hydroxyandrographolide (5), and andrographatoside (6), together with 17 known analogues, were isolated from the aerial parts of Andrographis paniculata. The structures of 1-6 were determined by spectroscopic data analysis. All compounds isolated were evaluated for their inhibitory activity against several bacterial and fungal strains. Andrographis paniculata Nees (Acanthaceae), a well-known herbal medicine, is cultivated widely in southern mainland China and used as an effective antibacterial and antiphlogistic agent in Chinese folk medicine.1 Extensive chemical and pharmaceutical investigations on this species have demonstrated that ent-labdane diterpenoids are the main bioactive components and have led to the clinical application of several antibacterial and anti-inflammatory drugs based on A. paniculata in the People’s Republic of China.2,3 More than 20 ent-labdane diterpenoids have been reported from A. paniculata.4-10 The present study on A. paniculanta has resulted in the isolation of six new ent-labdane diterpenoids (1-6), together with 17 known compounds of this series. The structures of compounds 1-6 were determined by extensive spectroscopic methods, including 1D and 2D NMR analysis. This paper reports the isolation, characterization, and antimicrobial screening of these diterpenoids. Moreover, compound 7 has been reported previously only as a product of solidphase synthesis without the publication of complete NMR data.11 Herein, we have assigned the NMR data of compound 7 through HMQC and HMBC experiments.

Results and Discussion The 70% acetone-water extract of the aerial parts of A. paniculata was partitioned between ethyl acetate and water, and then between n-butanol and water. The ethyl acetate- and n-butanolsoluble extracts were chromatographed sequentially over MCI-gel CHP-20P and silica gel columns and further purified by highperformance liquid chromatography (HPLC), using a reversed-phase column, to yield 23 compounds. Compound 1 was isolated as a white powder. The negative FABMS displayed a pseudomolecular ion [M - 1]- at m/z 479 and a fragment peak at m/z 317 [M - 1 - 162]-. The HRESIMS (m/z 479.2655 [M - 1]-), together with the NMR data, were used to determine the molecular formula of 1 as C26H40O8. The 1H and 13C NMR spectra of 1 (Table 1) exhibited signals for three tertiary methyls, an exocyclic methylene group, a R,β-unsaturated-γ-lactone, and a glucose, suggesting that compound 1 is a glucose derivative of an andrographolide analogue. When compared to the 13C NMR data of 14-deoxyandrographolide,4 the aglycon moiety of 1 showed the absence of a resonance for a hydroxymethylene for C-19 and the presence of a signal for an additional tertiary methyl (δC 17.0) ⊥ Dedicated to Dr. Norman R. Farnsworth of the University of Illinois at Chicago for his pioneering work on bioactive natural products. * To whom correspondence should be addressed. Tel: 86-871-5223251. Fax: 86-871-5216343. E-mail: [email protected]. † Kunming Institute of Botany, Chinese Academy of Sciences. ‡ Graduate School of the Chinese Academy of Sciences, Beijing.

10.1021/np050160u CCC: $33.50

Table 1.

13C

NMR Spectroscopic Data of Compounds 1-7

carbon

1

2

3

4

5

6

7

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1′ 2′ 3′ 4′ 5′ 6′ 1′′ 2′′ 3′′ 4′′ 5′′

37.0 t 24.3 t 84.8 d 38.9 s 55.1 d 24.3 t 38.4 t 148.3 s 56.3 d 39.5 s 22.3 t 25.1 t 134.2 s 145.7 d 70.8 t 174.8 s 107.2 s 28.8 q 17.0 q 14.7 q 102.5 d 75.2 d 78.7 d 72.1 d 78.5 d 63.3 t

37.2 t 28.6 t 80.3 d 43.1 s 55.2 d 21.9 t 31.8 t 42.4 d 52.2 d 38.0 s 27.5 t 27.7 t 134.3 s 145.6 d 70.7 t 174.8 s 64.9 t 23.7 q 64.5 t 15.1 q

38.9 t 19.2 t 35.9 t 38.5 s 56.1 d 24.4 t 38.4 t 148.3 s 56.5 d 39.6 s 22.0 t 24.9 t 134.2 s 145.5 d 70.5 t 174.5 s 107.1 t 28.1 q 71.9 t 15.4 q 103.8 d 78.7 d 78.8 d 72.0 d 78.2 d 62.8 t 110.9 d 78.0 d 80.7 s 75.7 t 66.3 t

37.1 t 23.8 t 85.5 d 43.5 s 55.7 d 24.7 t 38.3 t 148.1 s 56.3 d 39.1 s 25.1 t 147.1 d 130.2 s 66.0 d 75.5 t 170.9 s 108.8 t 23.6 q 63.7 t 14.9 q 101.3 d 75.2 d 78.7 d 71.9 d 78.7 d 63.1 t

37.9 t 29.0 t 81.0 d 43.7 s 56.6 d 25.4 t 39.4 t 149.2 s 53.9 d 40.3 s 30.3 t 71.0 d 53.8 d 73.6 d 76.5 t 178.4 s 107.9 t 23.4 q 65.0 t 15.7 q

39.3 t 20.6 t 38.6 t 44.8 s 56.8 d 26.5 t 39.2 t 148.8 s 56.3 d 41.0 s 23.2 t 34.7 t 142.9 s 127.5 d 58.6 t 60.1 t 106.9 t 29.0 q 176.6 s 13.7 q 95.8 d 74.1 d 79.1 d 71.1 d 79.4 d 62.3 t

37.9 t 28.4 t 80.9 d 43.6 s 56.0 d 22.8 t 37.6 t 60.0 s 54.5 d 41.0 s 21.2 t 27.8 t 134.5 s 147.8 d 72.1 t 177.0 s 51.4 t 23.4 q 64.9 t 15.7 q

and implied that the hydroxymethylene of C-19 in 14-deoxyandrographolide was converted into a tertiary methyl in 1. The glucose unit was linked to the C-3 position due to the observation of HMBC correlations between signals for the anomeric proton at δH 4.89 (1H, d, J ) 7.7 Hz) and C-3 (δC 84.8). Accordingly, the structure of 1 was assigned as 3-O-β-D-glucopyranosyl-14,19dideoxyandrographolide. Compound 2 was isolated as a white powder. The HRESIMS (m/z 375.2155 [M + Na]+) and the NMR data (Table 1) revealed the molecular formula as C20H32O5. Characteristic signals for two tertiary methyl groups (δH 0.78, 1.48) and an R,β-unsaturated-γlactone (δC 134.3, 145.6, 174.8) implied that 2 is an analogue of 14-deoxyandrographolide. The absence of any signal for an exocyclic methylene, along with the observation of resonances for an additional methine (δC 42.4) and a hydroxymethylene (δC 64.9), suggested that the double bond at C-8(17) is hydrogenated and substituted by a hydroxyl at C-17. This was confirmed by HMBC correlations (Figure 1) of H2-17 (δH 3.94 and 3.81) with C-7 (δC 31.8) and C-9 (δC 52.2). The relative configuration of the

© 2006 American Chemical Society and American Society of Pharmacognosy Published on Web 09/27/2005

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Figure 1. Key HMBC and ROESY correlations for compound 2. 17-hydroxymethylene was assigned with a β-orientation, on the basis of ROESY correlations (Figure 1) of H2-17 with H-9β (δH 0.95) and H-12a (δH 2.35). From these data, compound 2 was deduced to be 14-deoxy-17β-hydroxyandrographolide. Compound 3, a brown-yellow powder, exhibited a pseudomolecular ion at m/z 611 ([M - 1]-) and a fragment peak at m/z 479 ([M - 1 - 132]-) in the negative FABMS, consistent with the molecular formula, C31H48O12, which was confirmed by negative HRESIMS (m/z 611.3074 [M - 1]-). The 1H NMR spectrum of 3 exhibited characteristic resonances similar to those of andrographolide, including two tertiary methyl signals (δH 0.60, 1.26) and three sp2 proton signals (δH 4.69, 4.90, 7.18) for an exocyclic double bond and a trisubstituted double bond. The comparison of the 13C and DEPT spectroscopic data (Table 1) of 3 with those of neoandrographolide revealed the presence of an apiofuranosyl unit, 3.4,12 An HMBC experiment of 3 showed a long-range correlation between the anomeric proton H-1′′ of the apiose and the C-2′ (δC 78.7) of glucose, suggesting the apiosyl to be attached at C-2′ of the glucosyl moiety. Thus, compound 3 was determined as 19-O-[β-D-apiofuranosyl(1f2)-β-D-glucopyranoyl]-3,14-dideoxyandrographolide. Compound 4 was obtained as a white powder. The molecular formula of C26H40O10 was inferred from negative HRESIMS analysis ([M - 1]-, m/z 511.2537) and NMR data. Careful comparison of the NMR data of 4 with those of andrographolide indicated that 4 has one more glucose than andrographolide. The HMBC correlation of anomeric proton of glucose at δH 4.95 with C-3 (δC 85.5) suggested that the glucose is linked to the C-3 position of andrographolide. From the above observations, compound 4 was concluded to be 3-O-β-D-glucopyranosyandrographolide. The molecular formula of compound 5 was determined to be C20H32O6 from its HRESIMS (m/z 391.2086 [M + Na]+) and NMR data. The 1H NMR spectrum of 5 exhibited two tertiary methyl signals at δH 0.69 and 1.99, a pair of doublets at δH 4.09 and 3.33 (each 1H, d, J ) 10.8 Hz, H2-19) for a hydroxymethylene, two proton signals for an exocyclic double bond at δH 4.88 and 4.68 (each 1H, s, H2-17), and two doublets at 1.27 (1H, d, J ) 12.7 Hz, H-5β) and 1.72 (1H, d, J ) 11.2 Hz, H-9β), while the 13C and DEPT NMR data (Table 1) showed 20 carbon signals, including two methyls, eight methylenes, six methines, and four quaternary carbon signals. The NMR spectroscopic data of 5 were closely similar to those of andrographolide,4 except for the absence of signals for a trisubstituted double bond between C-12 and C-13 and the presence of resonances for two extra methines (δH 4.00, m and 2.43, t-like). The HMBC correlations (Figure 2) observed between the oxymethine signal at δH 4.00 and C-9 (δC 53.9), C-14 (δC 73.6), and C-16 (δC 178.4) implied a hydroxyl group at the C-12 position in 5. The C-12 chirality could be determined from the chemical shifts of the vinyl protons at C-17. Due to the deshielding effect of the hydroxyl group at C-12, the H-17 protons

in the 12S-isomer occur more downfield (near δH 4.7 ppm) than the corresponding protons (near δH 4.4 ppm) in the 12R-isomer.13 Compound 5, exhibiting two H-17 protons at δH 4.88 and 4.68, is considered to have 12S-chirality. Thus, compound 5 was determined as 12S-hydroxyandrographolide. Compound 6 was obtained as a white powder, and the molecular formula C26H42O9 was deduced from a pseudomolecular ion [M - 1]- at m/z 497 in the FABMS (negative) and from the NMR data and further confirmed by the negative HRESIMS (m/z 497.2764 [M - 1]-). The 1H NMR spectrum of 6 showed characteristic signals for two tertiary methyls (δH 0.92 and 1.28), one exocyclic double bond (δH 4.25 and 4.85), and one trisubstituted olefinic proton (δH 5.94, t, J ) 6.6 Hz), similar to most andrographolide derivatives, suggesting an ent-labdane skeleton. Besides the signals for a glucose moiety, the 13C and DEPT spectra of 6 (Table 1) also displayed a signal for an ester carbonyl (δC 176.6), ascribed to C-19, based on HMBC correlations (Figure 2) of H-3 (δH 2.40), H-5 (δH 1.32), and Me-18 with C-19. The HMBC correlation observed between the anomeric proton of glucose at

ent-Labdane Diterpenoids from Andrographis

Figure 2. Key HMBC correlations for compounds 5 and 6. δH 6.25 (1H, d, J ) 7.7 Hz) and C-19 indicated the linkage of glucose to C-19. The absence of an ester carbonyl at C-16 implied the opening of the γ-lactone ring and the formation of two hydroxymethylenes at C-15 and C-16, respectively. The geometrical configuration of the ∆13,14 double bond was determined to be cis on the basis of the ROESY correlations of H-14 with H-11 and H-12. Therefore, compound 6 was elucidated as 19-carboxylic acidO-β-D-glucopyranosyl-8(17),13-ent-labdadien-15,16-diol and named andrographatoside. The structures of the known compounds isolated were identified as 8,17-epoxy-14-deoxyandrographolide (7),11 andrographolide,4 andrographiside,4 andrograpanin) (8),5 neoandrographolide,4 14deoxy-11,12-didehydroandrographolide (9),4 14-deoxy-11,12-dihydroandrographiside,4 14-deoxy-12-hydroxyandrographolide (10),8 isoandrographolide (11),4 14-deoxyandrographolide,4 andropanoside,4 12-epi-14-deoxy-12-methoxyandrographolide,4 14-deoxy-12methoxyandrographolide,4 14-deoxy-11-oxoandrographolide,5 14deoxy-11-hydroxyandrographolide,4 bisandrogrpholide B,4 and bisandrographolide C,4 by comparison of their spectroscopic data with literature values. All diterpenoids were qualitatively evaluated for inhibitory activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Micrococcus luteus, Sarcina lutea, Candida albicans, Candida sake, and Aspergillus niger. Compounds 8-11 inhibited the growth of Bacillus subtilis and showed clear inhibition zones with a diameter of 7-8 mm at the minimal concentration (10 µg/mL) used. The other compounds were inactive against all organisms tested. Experimental Section General Experimental Procedures. Optical rotations were measured with a Horiba SEAP-300 spectropolarimeter. UV spectra were taken on a Shimadzu double-beam 210A spectrophotometer. 1H NMR,13C NMR, and 2D NMR spectra were recorded on a Bruker AM400 and a Bruker DRX-500 spectrometer with TMS as internal standard. MS were obtained on a VG Autospec-3000 spectrometer. Semipreparative HPLC was performed on an Agilent 1100 liquid chromatograph with a Zorbax SB-C18, 9.4 mm × 25 cm column. Preparative HPLC was performed on a Shimadzu LC-8A preparative liquid chromatograph with a Shimadzu PRC-ODS (K) column. Plant Material. The aerial parts of A. paniculata were purchased in Juhuacun herbal market, Kunming, Yunnan Province, People’s Republic of China, in October 2002, and were identified by one of the authors (Z.-W.L.). A voucher specimen (KIB-2002-10 Lin) was

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deposited at the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences. Extraction and Isolation. The dried and powdered aerial parts of A. paniculata (9 kg) were extracted with 70% Me2CO (3 × 25 L) at room temperature for 72 h and filtered. The filtrate was evaporated and partitioned, in turn, between H2O and EtOAc, and H2O and n-butanol. The EtOAc extract (300 g) was applied to column chromatography over MCI-gel CHP-20P (MeOH-H2O 9:1, 100% MeOH, 100% Me2CO). The 90% MeOH fraction (201 g) was chromatographed sequentially over silica gel (200-300 mesh, 1.5 kg), eluting with CHCl3Me2CO (1:0, 9:1, 8:2, 7:3, 6:4, 1:1, and 0:1) to afford fractions I-VII. Fraction I was chromatographed over silica gel (200-300 mesh) and Sephadex LH-20 and finally purified by semipreparative HPLC (MeOH-CH3CN-H2O, 10:35:55) to yield bisandrographolide B (122 mg) and bisandrographolide C (36 mg). Fraction II was repeatedly recrystallized with MeOH to afford 14-deoxy-11,12-didehydroandrographolide (7.746 g), and the mother liquor then was separated by semipreparative HPLC (MeOH-H2O, 50:50) to obtain 14-deoxy-12hydroxyandrographolide (21 mg). Fraction III was purified by recrystallization and repeated chromatography over silica gel, RP-18, and Sephadex LH-20 (MeOH), followed by semipreparative and preparative HPLC (MeOH-H2O, 45:55, 50:50), to yield compounds 8 (34.087 g) and 10 (494 mg). Fraction IV was repeatedly recrystallized with MeOH to afford compound 11 (18.452 g), and the mother liquor then was chromatographed sequentially over silica gel (eluting with CHCl3-MeOH, 20: 1, 9:1, 8:2, 7:3), RP-18 (MeOH-H2O, 30:70, 35:65, 40:60, 45:55, 50: 50, 60:40, 100:0), and Sephadex LH-20 (MeOH), followed by semipreparative and preparative HPLC (RP-18, MeOH-H2O 45:55, 50:50), to yield 5 (48 mg), 12-epi-14-deoxy-12-methoxyandrographolide (142 mg), and 14-deoxy-12-methoxyandrographolide (36 mg). Fraction V was subjected to column chromatography over silica gel, eluted with CHCl3-MeOH (9:1 and 8:2), to obtain 14-deoxy-11-hydroxyandrographolide (27 mg), and the mother liquor was purified by repeated chromatography over RP-18 (MeOH-H2O, 30:70, 35:65, 40:60, 45: 55, 50:50, 60:40, 100:0) and semipreparative and preparative HPLC (MeOH-H2O, 45:55, 50:50) to yield 7 (8 mg), isoandrographolide (211 mg), and 14-deoxyandrographolide (21 mg). Fraction VI was respectively purified with similar chromatographic methods, by using silica gel (CHCl3-MeOH 9:1) and Sephadex LH-20 (MeOH), followed by semipreparative and preparative HPLC (MeOH-CH3CN-H2O, 40:10: 50), to yield 9 (57 mg), 14-deoxy-11,12-dihydroandrographiside (47 mg), andropanoside (124 mg), and 14-deoxy-11-oxoandrographolide (4 mg). The n-butanol extract (161 g) was subjected to column chromatography over MCI-gel CHP 20P (90% MeOH-H2O, 100% MeOH, 100% Me2CO). The 90% MeOH fraction (130 g) was chromatographed over silica gel (200-300 mesh, 1.0 kg), eluting with a CHCl3-Me2CO (1: 0-1:1) gradient system, to give fractions 1-5. Fraction 1 was chromatographed over RP-18 (MeOH-H2O, 30:70, 35:65, 40:60, 45: 55, 50:50, and 100:0) and further purified by preparative HPLC (MeOH-H2O 35:65) to obtain 2 (72 mg). Fraction 2 was chromatographed sequentially over RP-18 (using MeOH-H2O gradient system), Sephadex LH-20 (100% MeOH), and preparative HPLC (MeOH-H2O, 35:65) to obtain 1 (25 mg) and 4 (33 mg). Fraction 4 was also chromatographed on a Sephadex LH-20 column (CHCl3-MeOH, 1:1) and then subjected to preparative HPLC (MeOH-H2O, 35:65) to afford 3 (13 mg) and 6 (21 mg). 3-O-β-D-Glucopyranosyl-14,19-dideoxyandrographo-lide (1): white powder; [R]25 D -51.0° (c 0.28, MeOH); UV (MeOH) λmax (log ) 204 (4.11) nm; 1H NMR (C5D5N, 500 MHz) δH 1.64 (1H, overlapped, H-1a), 0.98 (1H, overlapped, H-1b), 2.05 (1H, m, H-2a), 1.64 (1H, overlapped, H-2b), 3.51 (1H, dd, J ) 4.4, 12.1 Hz, H-3β), 0.98 (1H, overlapped, H-5β), 1.48 (1H, m, H-6a), 1.30 (1H, m, H-6b), 2.36 (1H, m, H-7a),1.92 (1H, m, H-7b), 1.57 (1H, d, J ) 11.5 Hz, H-9β), 1.71 (1H, m, H-11a), 1.64 (1H, overlapped, H-11b), 2.53 (1H, m, H-12a), 2.31 (1H, m, H-12b), 6.97 (1H, s, H-14), 4.78 (2H, s, H2-15), 4.90 (1H, s, H-17a), 4.74 (1H, s, H-17b), 1.17 (3H, s, Me-18), 0.86 (3H, s, Me-19), 0.64 (3H, s, Me-20), 4.89 (1H, d, J ) 7.7 Hz, H-1′), 3.99 (1H, overlapped, H-2′), 3.99 (1H, overlapped, H-3′), 4.21 (1H, t, J ) 9.3 Hz, H-4′), 4.28 (1H, t, J ) 9.5 Hz, H-5′), 4.58 (1H, d, J ) 11.5 Hz, H-6′a), 4.37 (1H, dd, J ) 5.5, 11.5 Hz, H-6′b); 13C NMR (C5D5N, 125 MHz), see

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Table 1; FABMS (negative) m/z 479 [M - 1]-, 317 [M - 1 - 162]-; HRESIMS (negative) m/z 479.2655 [M - 1]- (calcd 479.2644 for C26H39O8). 14-Deoxy-17β-hydroxyandrographolide (2): white powder; [R]25 D -9.4° (c 0.80, MeOH); UV (MeOH) λmax (log ) 208 (4.08) nm; 1 H NMR (C5D5N, 500 MHz) δH 1.82 (1H, m, H-1a), 1.02 (1H, dd, J ) 3.7, 13.3 Hz, H-1b), 2.02 (1H, m, H-2a), 1.93 (1H, m, H-2b), 3.62 (1H, dd, J ) 4.1, 11.0 Hz, H-3β), 0.98 (1H, d, J ) 11.0 Hz, H-5β), 1.76 (1H, d, J ) 12.8 Hz, H-6a), 1.32 (1H, m, H-6b), 2.19 (1H, m, H-7a), 1.45 (1H, overlapped, H-7b), 1.45 (1H, overlap, H-8R), 0.95 (1H, m, H-9β), 1.67 (1H, m, H-11a), 1.38 (1H, m, H-11b), 2.65 (1H, brt, H-12a), 2.35 (1H, m, H-12b), 7.21 (1H, brs, H-14), 4.75 (2H, s, H2-15), 3.94 (1H, d, J ) 10.6 Hz, H-17a), 3.81 (1H, dd, J ) 4.1, 10.6 Hz, H-17b), 1.48 (3H, s, Me-18), 4.98 (1H, d, J ) 10.6 Hz, H-19a), 3.64 (1H, d, J ) 10.6 Hz, H-19b), 0.78 (3H, s, Me-20); 13C NMR (C5D5N, 100 MHz), see Table 1; FABMS (positive) m/z 353 [M + 1]+; HRESIMS (positive) m/z 375.2155 [M + Na]+ (375.2147 for C20H32O5Na). 19-O-[β- D -Apiofuranosyl(1f2)-β- D -glucopyranoyl]-3,14-dideoxyandrographolide (3): brown-yellow powder; [R]26 D -57.1° (c 0.32, MeOH); UV (MeOH) λmax (log ) 204 (4.21) nm; 1H NMR (C5D5N, 500 MHz) δH 1.60 (1H, overlapped, H-1a), 0.93 (1H, overlapped, H-1b), 1.60 (1H, overlapped, H-2a), 1.31 (1H, d, J ) 14.3 Hz, H-2b), 2.33 (1H, d, J ) 13.2 Hz, H-3a), 0.93 (1H, overlapped, H-3b), 1.13 (1H, d, J ) 13.2 Hz, H-5β), 1.75 (1H, m, H-6a), 1.21 (1H, m, H-6b), 2.33 (1H, d, J ) 7.6 Hz, H-7a), 1.88 (1H, m, H-7b), 1.60 (1H, overlapped, H-9β), 1.70 (1H, m, H-11a), 1.60 (1H, overlapped, H-11b), 2.49 (1H, m, H-12a), 2.17 (1H, m, H-12b), 7.18 (1H, s, H-14), 4.75 (2H, s, H2-15), 4.90 (1H, overlapped, H-17a), 4.69 (1H, s, H-17b), 1.26 (3H, s, Me-18), 4.32 (1H, d, J ) 9.9 Hz, H-19a), 3.41 (1H, d, J ) 9.9 Hz, H-19b), 0.60 (3H, s, Me-20), 4.77 (1H, d, J ) 7.7 Hz, H-1′), 4.15 (1H, t, J ) 8.2 Hz, H-2′), 4.25 (1H, t, J ) 8.2 Hz, H-3′), 4.12 (1H, t, J ) 9.4 Hz, H-4′), 3.85 (1H, m, H-5′), 4.48 (1H, d, J ) 11.5 Hz, H-6′a), 4.30 (1H, d, J ) 11.5 Hz, H-6′b), 6.45 (1H, s, H-1′′), 4.90 (1H, overlapped, H-2′′), 4.71 (1H, d, J ) 9.4 Hz, H-4′′a), 4.40 (1H, d, J ) 9.4 Hz, H-4′′b), 4.23 (2H, s, H-5′′); 13C NMR (C5D5N, 125 MHz), see Table 1; FABMS (negative) m/z 611 [M 1]-, 479 [M - 1 - 132]-; HRESIMS (negative) m/z 611.3074 [M 1]- (calcd 611.3067 for C31H47O12). 3-O-β-D-Glucopyranosyandrographolide (4): white powder; [R]25 D -80.3° (c 0.48, MeOH); UV (MeOH) λmax (log ) 203 (4.05), 221 (4.03) nm; 1H NMR (C5D5N, 400 MHz) δH 1.65 (1H, t, J ) 12.3 Hz, H-1a), 1.05 (1H, t, J ) 12.3 Hz, H-1b), 2.14 (2H, m, H2-2), 3.81 (1H, dd, J ) 3.8, 11.8 Hz, H-3β), 1.14 (1H, d, J ) 12.1 Hz, H-5β), 1.79 (1H, m, H-6a), 1.39 (1H, m, H-6b), 2.28 (1H, m, H-7a), 1.87 (1H, m, H-7b), 1.79 (1H, overlapped, H-9β), 2.68 (2H, m, H2-11), 7.16 (1H, d, J ) 6.0 Hz, H-12), 5.38 (1H, brs, H-14), 4.63 (1H, d, J ) 10.1 Hz, H-15a), 4.53 (1H, d, J ) 10.1 Hz, H-15b), 4.85 (1H, brs, H-17a), 4.83 (1H, brs, H-17b), 1.45 (3H, s, Me-18), 4.26 (1H, d, J ) 9.8 Hz, H-19a), 3.58 (1H, d, J ) 9.8 Hz, H-19b), 0.63 (3H, s, Me-20), 4.95 (1H, d, J ) 7.6 Hz, H-1′), 3.96 (1H, m, H-2′), 4.28 (1H, m, H-3′), 4.15 (1H, m, H-4′), 4.01 (1H, m, H-5′), 4.59 (1H, m, H-6′a), 4.38 (1H, m, H-6′b); 13C NMR (C5D5N, 100 MHz), see Table 1; FABMS (negative) m/z 511 [M - 1]-; HRESIMS (negative) m/z 511.2537 [M - 1]- (calcd 511.2543 for C26H39O10). 12S-Hydroxyandrographolide (5): white powder; [R]25 D -82.1° (c 0.32, MeOH); UV (MeOH) λmax (log ) 203 (3.83) nm; 1H NMR (CD3OD, 500 MHz) δH 1.87 (1H, m, H-1a), 1.36 (1H, m, H-1b), 1.77 (2H, m, H2-2), 3.39 (1H, t, J ) 8.3 Hz, H-3β), 1.27 (1H, d, J ) 12.7 Hz, H-5β), 1.83 (1H, m, H-6a), 1.33 (1H, m, H-6b), 2.40 (1H, m, H-7a), 1.98 (1H, m, H-7b), 1.72 (1H, d, J ) 11.2 Hz, H-9β), 2.21 (1H, m, H-11a), 1.62 (1H, m, H-11b), 4.00 (1H, m, H-12), 2.43 (1H, t-like, H-13), 4.38 (1H, m, H-14), 4.44 (1H, dd, J ) 4.9, 9.4 Hz, H-15a), 4.05 (1H, dd, J ) 2.0, 9.4 Hz, H-15b), 4.88 (1H, s, H-17a), 4.68 (1H, s, H-17b), 1.99 (3H, s, Me-18), 4.09 (1H, d, J ) 10.8 Hz, H-19a), 3.33 (1H, d, J ) 10.8 Hz, H-19b), 0.69 (3H, s, Me-20); 13C NMR (CD3OD, 100 MHz), see Table 1; EIMS (70 ev) m/z 368 (1) [M]+, 350 (1), 332 (5), 314 (5), 309 (7), 296 (10), 291 (12), 284 (17), 219 (20), 201 (34), 189 (27), 173 (45), 159 (46), 145 (50), 133 (57), 121 (100), 105 (74), 93 (70), 81 (46); HRESIMS (positive) m/z 391.2086 [M + Na]+ (calcd 391.2096 for C20H32O6Na).

Shen et al.

Andrographatoside (6): white powder; [R]26 D -29.8° (c 0.35, MeOH); UV (MeOH) λmax (log ) 204 (4.03) nm; 1H NMR (C5D5N, 500 MHz) δH 1.83 (1H, overlapped, H-1a), 1.02 (1H, m, H-1b), 2.13 (1H, overlapped, H-2a), 1.32 (1H, brd, H-2b), 2.40 (1H, overlapped, H-3β), 1.32 (1H, d, J ) 12.5 Hz, H-5β), 2.40 (1H, overlapped, H-6a), 2.13 (1H, overlapped, H-6b), 1.95 (2H, m, H2-7), 1.83 (1H, overlapped, H-9β), 1.83 (1H, overlapped, H-11a), 1.67 (1H, m, H-11b), 2.69 (1H, m, H-12a), 2.24 (1H, m, H-12b), 5.94 (1H, t, J ) 6.6 Hz, H-14), 4.65 (2H, d, J ) 6.6 Hz, H2-15), 4.58 (1H, d, J ) 12.7 Hz, H-16a), 4.53 (1H, d, J ) 12.7 Hz, H-16b), 4.85 (1H, s, H-17a), 4.25 (1H, s, H-17b), 1.28 (3H, s, Me-18), 0.92 (3H, s, Me-20), 6.25 (1H, d, J ) 7.7 Hz, H-1′), 4.15 (1H, t, J ) 8.8 Hz, H-2′), 4.22 (1H, t, J ) 8.8 Hz, H-3′), 4.29 (1H, d, J ) 9.3 Hz, H-4′), 3.97 (1H, m, H-5′), 4.41 (1H, dd, J ) 2.2, 12.1 Hz, H-6′a), 4.34 (1H, dd, J ) 4.4, 12.1 Hz, H-6′b); 13C NMR (C5D5N, 125 MHz), see Table 1; FABMS (negative) m/z 497 [M 1]-; HRESIMS (negative) m/z 497.2764 [M - 1]- (calcd 497.2750 for C26H41O9). 8,17-Epoxy-14-deoxyandrographolide (7): white powder; [R]24 D -5.7° (c 0.28, MeOH); UV (MeOH) λmax (log ) 208 (3.93) nm; 1H NMR (CD3OD, 400 MHz) δH 1.78 (1H, m, H-1a), 1.20 (1H, overlapped, H-1b), 1.73 (2H, m, H2-2), 3.37 (1H, t-like, H-3β), 1.20 (1H, overlap, H-5β), 1.89 (1H, m, H-6a), 1.58 (1H, m, H-6b), 1.37 (2H, m, H2-7), 1.45 (1H, overlap, H-9β), 1.45 (1H, overlapped, H-11a), 1.04 (1H, m, H-11b), 2.32 (1H, m, H-12a), 2.20 (1H, m, H-12b), 7.34 (1H, t, J ) 1.4 Hz, H-14), 4.79 (1H, d, J ) 1.4 Hz, H-15), 2.80 (1H, dd, J ) 1.8, 4.0 Hz, H-17a), 2.50 (1H, d, J ) 4.0 Hz, H-17b), 1.21 (3H, s, Me-18), 4.08 (1H, d, J ) 10.1 Hz, H-19a), 3.39 (1H, d, J ) 10.1 Hz, H-19b), 0.83 (3H, s, Me-20); 13C NMR (CD3OD, 100 MHz), see Table 1; FABMS (positive) m/z 351 [M + 1]+; HRESIMS (positive) m/z 373.1989 [M + Na]+ (373. 1990 for C20H30O5Na). Antimicrobial Testing. All diterpenoids were tested for inhibitory activity against eight microbial strains, namely, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Micrococcus luteus, Sarcina lutea, Candida albicans, Candida sake, and Aspergillus niger at a concentration 10 µg/mL, using a disk diffusion assay on agar plates, as described previosly.14 Acknowledgment. The authors are grateful to Prof. C.-L. Jiang and Dr. Y.-G. Chen of Yunnan University, Kumming, People’s Republic of China, for the antimicrobial testing assay. Supporting Information Available: This material is available free of charge via the Internet at http://pubs.acs.org. References and Notes (1) Wu, C. Y. Xinhua Herbal Outline, 1st ed.; Shanghai Science and Technology Press: Shanghai, 1994; Vol. 2, pp 481-482. (2) Committee of the National Pharmacopoeia. The Pharmacopoeia of People’s Republic of China; Chemical Industry Press: Beijing, 2000; Vol. 1, pp 541-542. (3) Huang, T. K. Handbook of Composition and Pharmacological Action of Commonly used Traditional Chinese Medicine; China Medicine Science and Technology Press: Beijing, 1994; pp 1462-1467. (4) Matsud, T.; Kuroyanagi, M.; Sugiyama, S.; Umehara, K.; Ueno, A.; Nishi, K. Chem. Pharm. Bull. 1994, 42, 1216-1225. (5) Fujita, T.; Fujitani, R.; Takeda, Y.; Takaishi, Y.; Yamada, T.; Kido, M.; Miura, I. Chem. Pharm. Bull. 1984, 32, 2117-2125. (6) Jantan, I.; Waterman, P. G. Phytochemistry 1994, 37, 1477-1479. (7) Zhong, D. X.; Xuan, L. J.; Xu, Y. M.; Bai, D. L. Acta Bot. Sin. 2001, 43, 1077-1080. (8) Zhang, S. J.; Ando, M. Chin. J. Med. Chem. 1997, 7, 270-273. (9) Hu, C. Q.; Zhou, B. N. Acta Pharm. Sin. 1982, 17, 435-439. (10) Reddy, M. K.; Reddy, M. V. B.; Gunasekar, D.; Murthy, M. M.; Caux, C.; Bodo, B. Phytochemistry 2003, 62, 1271-1275. (11) Biabani, M. A. F.; Grover, R. K.; Singh, S. K.; Kumar, S.; Raj, K.; Roy, R.; Kundu, B. Tetrahedron Lett. 2001, 42, 7119-7121. (12) Niu, X. M.; Li, S. H.; Wu, L. X.; Gao, L. H.; Sun, H. D. Planta Med. 2004, 70, 578-581. (13) Shieh, Y. L.; Fang, J. M.; Cheng, Y. S. Phytochemistry 1998, 47, 845-850. (14) Espinel-Ingroff, A.; White, T.; Pfaller, M. A. In Antifungal Agents and Susceptibility Test Manual of Clinical Microbiology, 7th ed.; Murray, P. R., Ed.; American Society for Microbiogy: Washington, D.C., 1999; pp 1640-1652.

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